When you're good at what your taught so Riot changes the rules.
I think we can all agree that as a whole, the community has gotten better hence the whole "plat is the new gold", "Gold is the new silver" etc. The community has learned basic things that have made them better over all.
One of those core skills of being a good player is warding. For years we tried to teach people (I.E. Beg) to ward. Warding saves lives. It got to the point that people were getting so good at warding that Riot literally had to change how wards work and even how stealth works in general.
Games where people are actually doing what they are suppose to aren't fun to watch. Watching a jungle walk past 3 wards to sit in river bush for 30s waiting for the enemy to make a mistake not realizing they know he is there the whole time and just giving him enough "hope" to deny him xp is boring streaming.
So Riot creates scanners to allow you to remove enemy wards, Pinks became visible (i.e. Useless) which rewarded your 75g with watching it being killed by the enemy team and giving them 30g and stealth just pretty much shits on you and your attempt to "play well" by having invisible characters walk right up to you, past the wards you placed down to prevent such a thing and kill you.
Riot employee 1: Games are getting boring, people are warding. How do we punish good play?
Riot employee 2: What if we made/change champs to ignore all the things players do to protect themselves?
Riot employee 1: Brilliant!